1. Field of Invention
The invention relates to a positive crankcase ventilation (PCV) system for an internal combustion engine.
2. Description of Related Art
During the operation of reciprocating engines such as internal combustion engines and compressors, small volumes of gaseous media may be forced past sealing rings into the crankcase. This gaseous media, which is also called blow-by gas, can comprise both pre-combustion and post-combustion gases and may further include oil, water vapor, etc.
The build up of blow-by gases within the crankcase and the attendant build up of gas pressure may cause damage to engine components such as seals and gaskets. Further, blow-by gases, which often include a mixture of unburned fuel and intake air, are typically corrosive. Thus, in order to maximize fuel efficiency, minimize the discharge of unburned fuel to the environment, and minimize damage caused by blow-by gas retention within the crankcase, it is known to ventilate the crankcase and re-circulate the blow-by gases to the intake side of the engine to be burned in the combustion chambers.
Positive crankcase ventilation (PCV) systems are used to ventilate the crankcase and re-circulate the blow-by gases to the intake side of the engine where these gases can be combined with fresh air entering via the air induction system. With respect to the gas pressure in the crankcase, a relative negative pressure in the air intake is typically used to draw blow-by gases out of crankcase and into the air intake.
An external conduit, such as a vent line issuing from the crankcase and connecting to an inlet port of a PCV channel, can be used to route the blow-by gases from the crankcase to the PCV channel which, in turn, distributes the gases into the air induction system. Preferably, the blow-by gases are uniformly introduced to the airflow and thus uniformly distributed to each of the engine's cylinders.
Gas flow from the crankcase can be regulated using a valve (i.e., a PCV valve) which opens when the gas pressure in the crankcase exceeds a predetermined value. Ideally, blow-by gases are removed from the crankcase at the same rate they enter without upsetting the fuel/air mixture for combustion.
Due to under-hood space limitations in most automobile applications, it would be advantageous to provide a positive crankcase ventilation (PCV) channel that is integrated into the construction of an air manifold. It would also be advantageous to provide a positive crankcase ventilation system having a minimal number of additional parts and/or a minimal number of manufacturing steps.